Plants, which are highly known for their tolerance, can withstand any inhospitable and challenging climate, are categorized as CAM plants. They are basically called CAM plants because of the carbon fixation method they adopt to survive dry circumstances.
The carbon fixation method called CAM stands for “Crassulacean Acid Metabolism,” and the process is termed CAM photosynthesis. Now the question arises: What is CAM photosynthesis, and how does it differ from the normal photosynthesis process.
This article will clarify the difference between regular plants and CAM plants and in-depth detail of CAM photosynthesis.
Firstly let’s talk about regular photosynthesis. The stomata on the leaves’ surface open during the daytime to take in CO2 to prepare sugars, proteins, and nucleotides and gives out O2 as a waste product in the environment. During this process, as the stomata are open, water is also transpired.
Nonetheless, plants need water to thrive. Growing in an arid environment, over the years, plants have evolved and adapted many physiological characteristics to withstand a diverse range of climatic conditions ranging from scorching deserts to cloud forests.
In the plants growing and dealing with an extremely dry environment, CAM is considered an ecophysiological syndrome, which is of great benefit.
What exactly happens after the plant’s adaptations, i.e., in CAM plants, to avoid the intense loss of water during the day because of the hot weather, the stomata tends to stay closed. At night when the weather is a bit cool, stomata open takes in CO2 and store it as “malate” with a far less loss of water.
This four-carbon acid malate is then released during the day to bind with the energy units made by the sun’s energy. In this way, CAM plants can conserve a large amount of water and survive in parched places.
Now the question arises what is the first step in cam photosynthesis? Cam photosynthesis can be briefly explained in four stages as given below:
What is the first step in CAM photosynthesis?
Cam photosynthesis begins at night, during which the stomata open and allows CO2 to enter the mesophyll cells in which it reacts with the hydroxyl ion OH- to for bicarbonates in the presence of enzyme phosphoenolpyruvate carboxylase (PEP carboxylase)
CO2 + OH– HCO3–
The phosphoenolpyruvate carboxylase enzyme boosts the reaction between carbon dioxide and phosphoenolpyruvate to produce oxaloacetate.
PEP + HCO3– Oxaloacetate
The oxaloacetates thus formed gains an electron from NADH and converts into a molecule of malate.
Oxaloacetate + NADH Malate,
An enzyme malate dehydrogenase boosts up the reaction. The response is reversible so that it can convert either oxaloacetate to malate or vice versa.
When photosynthesis begins, the malate, which was previously stored in the vacuoles, enters the Calvin cycle. The remaining process of CAM photosynthesis is completed afterward.
Some other characteristics of CAM plants:
In addition to the difference in the photosynthesis process, CAM plants also have some exclusive characteristics that help them survive in rough and harsh environments.
- They are usually succulent plants.
- Some of them shed their leaves in the dry season, while others store water in their vacuoles.
- CAM plant have a unique character because they are sour at night; however, much sweeter during the daytime.
- CAM plants have adapted a thick cuticle, and the stomata are deep under the pits to restrict the water loss through transpiration.
CAM plants got their name CAM because of the first plant Crassula in which CAM metabolism was discovered and was studied extensively.
Examples of CAM plants
CAM plants comprise up to 8% of the total land plants and are widely distributed in up to 40 families and about 20,000 species. They are either monocots or dicots. The most common examples of CAM plants include
One of the most common CAM plant which is widely used indoors is the Jade plant. It is an evergreen plant, which is also called a money plant, money tree, or lucky tree. It is a succulent plant with pink and white flowers. It can thrive with minimum care and attention and a very little supply of water.
The plant has thick branches and shiny, thick leaves which are bright green; some may have a combination of yellow, green leaves while others develop a red tint at the tip of leaves when exposed to sunlight.
Jade plant is a bit toxic to dogs, cats, horses and can cause skin irritation in humans.
The plant does not need a lot of care and maintenance. However, the water supply should be kept under control as overwatering can cause root rot and fall. It can survive with a minimum amount of water in summers and even less in winters.
Make sure you use pot soil with good drainage. A nice trim at regular intervals helps the plant to grow rapidly. The plant is prone to infection by scale insects that can even deform the jade plant. The insect should be killed and removed by using cotton or brush dipped in rubbing alcohol.
Cacti are unique CAM plant that is succulent, and can even survive an intense shortage of water. It is called the desert plant. These plants use CAM photosynthesis to stay in a rough climate.
Typically they have rounded shapes to naturally minimize the surface area and preventing water loss through transpiration. The spiny plants are available in various shapes and sizes and have thick fleshy parts adapted efficiently to store water.
Cacti typically lose their leaves, and the stems enlarge for vital processes such as photosynthesis. These stems are ribbed, which helps them to expand and contract to absorb water quickly after rain.
The spines of cacti protect it from water loss as they decrease the airflow around the cacti. Cacti are used for several ornamental purposes. A wide variety of these CAM plants are also used as a food source for humans and animals after burning their spines.
Agave is a monocot plant that grows in a rough and hot climate and is generally perennial as they take a lot of years to mature. Many species of agave flower only once in a lifetime and dies afterward.
It is one of the most popular CAM plants which are used in the production of tequila. It is also used to produce delightful agave nectar. The plant is also used as a food source by the larva of insects, including moths and butterflies.
Agave is very much similar to cacti except that it is more leafy and green than cacti. It has sharp spines that protect the plant from being eaten by wild animals.
A tropical plant is known for its edible and incredibly delicious fruit; pineapple also undergoes CAM metabolism to survive arid conditions. Typically, pineapple grows as a small shrub, and the plant often matures within a year.
Moreover, pineapple provides a lot of nutrition in different forms, such as raw pulp, water, proteins, and fats. The flesh and juice of pineapple is a rich source of vitamin C and minerals, especially manganese.
The CAM plant is vulnerable to several diseases; the most common is the wilting disease. It is caused by specific bugs named mealy bugs. Special measures should be taken to protect your plant from the damages caused by pests.
The mouth-watering fruit is used worldwide in many cuisines or the form of juice. In a lot of countries, pineapple is sold as a snack on the roads. It is also considered the main ingredients of cocktails.
Orchids are the CAM plants widely used for ornamental purposes because of the exciting colors and beautiful sight their flowers present.
The plants have bilateral symmetry and a large number of flowers. The orchids are extremely low maintenance plants as they can survive a very rough climate. Different varieties of orchids are categorized as facultative CAM plants as they can adapt CAM metabolism when subjected to extremely dry and hot climate conditions.
The plants are susceptible to overwatering and overfeeding, which may lead to extensive damages. Therefore make sure that if you have orchids at your home, do not overwater them and fertilize them once a week.
The Wax plant, also called a porcelain flower, is a flowering plant famous for its waxy foliage. The sweet fragrance of the flowers makes them the best choice to be grown indoors. It is most commonly used for decorative purposes in the house.
These tropical plants have a long life and can survive arid conditions by adapting the CAM metabolism process. The two exquisite flowers are a feast to the eyes, and they display a perfect sight which looks very beautiful.
The wax plants need a fair amount of bright sunlight but not directly, as this may affect the leaves. These plants are rare.
An epiphyte that usually grows on large trees, Spanish moss, consists of thin stems and scaled leaves. The plant does not have any aerial roots and extends through spread by wind, sticking to trees’ limbs.
Spanish moss is considered as CAM plants because of their ability to adapt to the water shortage and also to withstand dry climate by changing the mechanism of photosynthesis. These plants are used for many purposes, including packaging material, preparing stuffed mattresses, and manufacturing insulations of the buildings.
When dried, these plants are used in the production of desert coolers, also called evaporative coolers.
Aloe Vera is a facultative CAM plant. It can undergo regular photosynthesis and CAM photosynthesis; it can adapt to any climatic conditions. Aloe Vera is a tropical plant that grows wildly and can also be cultivated for many benefits.
Aloe Vera can also be grown in home gardens. It is a plant with substantial medical importance; many skin problems can be treated using the magical gel of this CAM plant. It is also used in mouthwashes and mouth fresheners. The exciting fact is that it is a very low maintenance plant and can survive harsh conditions.
Coming towards the conclusion, the plants which perform CAM photosynthesis, inverting the normal process of stomatal opening to survive in intensely hot and dry areas are the CAM plant. The CAM metabolism enables the plant to survive the inhospitable climate. Thereby, it minimizes the plant’s transpiration and helps them to preserve water.